Abstract: A method and apparatus are disclosed from the perspective of an User Equipment (UE). In one embodiment, the method includes the UE performing sensing on a second direction or beam. The method also includes the UE performing a sidelink transmission on a resource on a first direction or beam, wherein the resource is selected based on at least sensing result of the second direction or beam.

Abstract: A method and device are disclosed for a remote User Equipment (UE) to receive system information. In one embodiment, the method includes the remote UE receiving a system information from a network node via a relay UE, wherein a sidelink transmission of the system information is sent with a common Layer-2 Identity (ID) as Destination Layer-2 ID and a Layer-2 ID of the relay UE as Source Layer-2 ID, and wherein the common Layer-2 ID is associated with a purpose of delivering or forwarding the system information from the network node.

Abstract: A method and device are disclosed from the perspective of a second UE. The second UE initiates a first procedure of establishing the one-to-one connection with the first UE for a unicast communication between the first UE and the second UE or for a UE-to-UE communication between the first UE and a third UE via the second UE or a second procedure of establishing the one-to-one connection with the first UE for a UE-to-Network communication between the first UE and a network node via the second UE. The second UE transmits a first PC5-S message to the first UE for completing the first procedure of establishing the one-to-one connection with the first UE for the unicast communication or the UE-to-UE communication if the first procedure is initiated, wherein the first PC5-S message includes QoS information for the unicast communication or the UE-to-UE communication.

Abstract: A method and apparatus are disclosed from the perspective of a first User Equipment (UE) to request dedicated sidelink configuration. In one embodiment, the method includes the first UE transmitting a first Radio Resource Control (RRC) message to a network node, wherein the first RRC message includes a sidelink Quality of Service (QoS) information, and wherein a presence of an identity of a sidelink QoS flow in the sidelink QoS information is mandatory and a presence of a QoS profile of the sidelink QoS flow in the sidelink QoS information is optional. The method also includes the first UE receiving a second RRC message from the network node, wherein the second RRC message includes a dedicated sidelink configuration and the identity of the sidelink QoS flow associated with the dedicated sidelink configuration.

Abstract: A method and apparatus are disclosed from the perspective of a User Equipment (UE) for the UE to request sidelink resources for an one-to-one V2X (Vehicle-to-Everything) sidelink communication, wherein the UE supports both LTE (Long Term Evolution) RAT (Radio Access Technology) and NR (New Radio) RAT. In one embodiment, the method includes the UE initiating a one-to-one V2X sidelink communication. The method further includes the UE transmitting a RRC (Radio Resource Control) message to a network node to request sidelink resources from NR RAT for the one-to-one V2X sidelink communication and not transmitting any RRC message to the network node to request sidelink resources from LTE RAT for the one-to-one V2X sidelink communication.

Abstract: A method and apparatus are disclosed from the perspective of a first device to determine sidelink feedback resource associated with sidelink communication. In one embodiment, the method includes the first device receiving an identifier from an upper layer of the first device. The method also includes the first device receiving a sidelink transmission from a second device. The method further includes the first device determining a sidelink feedback resource associated with the sidelink transmission at least based on the identifier and a source ID (Identity) associated with the sidelink transmission. In addition, the method includes the first device using the sidelink feedback resource to transmit a feedback in response to the sidelink transmission to the second device.

Abstract: A method and device are disclosed for adaptation layer configuration, wherein an adaptation layer is above a Uu Radio Link Control (RLC) layer and below a Uu Packet Data Convergence Protocol (PDCP) layer. In one embodiment, the method includes a network node transmitting a first Radio Resource Control (RRC) message including an adaptation layer configuration or an information for a Uu logical channel to a relay User Equipment (UE), wherein a field in the adaptation layer configuration indicates whether or not an adaptation layer header is present for the Uu logical channel and a value of the field cannot be changed after the Uu logical channel is established, and wherein the information indicates whether or not an adaptation layer is established for the Uu logical channel and the information cannot be changed after the Uu logical channel is established.

Abstract: A method and apparatus are disclosed from the perspective of a first UE (User Equipment) to perform sidelink logical channel (SL LCH) establishment. In one embodiment, the method includes the first UE storing a list of sidelink configurations, wherein each entry in the list contains one sidelink configuration and at least one PC5 QoS identifier (PQI) associated with the one sidelink configuration. The method further includes the first UE selecting an entry in the list according to a PQI of a PC5 QoS flow from a sidelink service. The method also includes the first UE establishing a SL LCH for the PC5 QoS flow according to a sidelink configuration of the entry and assigning an identity for the SL LCH.

Abstract: A method and device are disclosed from the perspective of a first UE. The first UE initiates a first procedure of establishing the one-to-one connection with the second UE for a unicast communication between the first UE and the second UE or for a UE-to-UE communication between the first UE and a third UE via the second UE or a second procedure of establishing the one-to-one connection with the second UE for a UE-to-Network communication between the first UE and a network node via the second UE. The first UE transmits a first PC5-S message to the second UE for completing establishment of a first security context in the first procedure of establishing the one-to-one connection with the second UE for the unicast communication or the UE-to-UE communication if the first procedure is initiated, wherein the first PC5-S message includes QoS information for the unicast communication or the UE-to-UE communication.

Abstract: A method and apparatus are disclosed from the perspective of a UE. In one embodiment, the method includes receiving a first signaling, wherein the first signaling includes an identity of a broadcast or multicast service. The method further includes receiving a second signaling, wherein the second signaling indicates an association between a numerology and an information of the broadcast or multicast service. The method also includes using the numerology to receive the broadcast or multicast service.

Abstract: A method and device are disclosed from the perspective of a second UE. The second UE initiates a first procedure of establishing the one-to-one connection with the first UE for a unicast communication between the first UE and the second UE or for a UE-to-UE communication between the first UE and a third UE via the second UE or a second procedure of establishing the one-to-one connection with the first UE for a UE-to-Network communication between the first UE and a network node via the second UE. The second UE transmits a first PC5-S message to the first UE for completing the first procedure of establishing the one-to-one connection with the first UE for the unicast communication or the UE-to-UE communication if the first procedure is initiated, wherein the first PC5-S message includes QoS information for the unicast communication or the UE-to-UE communication.

Abstract: A method and apparatus are disclosed from the perspective of a first UE (User Equipment) to perform sidelink logical channel (SL LCH) establishment. In one embodiment, the method includes the first UE storing a list of sidelink configurations, wherein each entry in the list contains one sidelink configuration and at least one PC5 QoS identifier (PQI) associated with the one sidelink configuration. The method further includes the first UE selecting an entry in the list according to a PQI of a PC5 QoS flow from a sidelink service. The method also includes the first UE establishing a SL LCH for the PC5 QoS flow according to a sidelink configuration of the entry and assigning an identity for the SL LCH.

Abstract: A method and apparatus are disclosed from the perspective of a transmitting device. In one embodiment, the method includes being configured or allocated with an identity, wherein the identity comprises a first part of the identity and a second part of the identity. The method also includes the transmitting device generating a data packet for sidelink transmission, wherein the data packet includes the second part of the identity. Furthermore, the method includes transmitting device generating a control information associated with the data packet, wherein the control information includes the first part of the identity. The method further includes the transmitting device transmits the control information and the data packet.

Abstract: A method and apparatus are disclosed from the perspective of a communication device. In one embodiment, the method includes the device being configured with a plurality of resource pools by a base station for a cell. The method further includes the device receiving a grant from the base station, wherein the grant indicates a resource associated with a resource pool of the plurality of resource pools through a resource pool index in the grant. The method also includes the device using the resource to perform a transmission on a device-to-device interface.

Abstract: A method and apparatus are disclosed from the perspective of a transmitting device. In one embodiment, the method includes being configured or allocated with an identity, wherein the identity comprises a first part of the identity and a second part of the identity. The method also includes the transmitting device generating a data packet for sidelink transmission, wherein the data packet includes the second part of the identity. Furthermore, the method includes transmitting device generating a control information associated with the data packet, wherein the control information includes the first part of the identity. The method further includes the transmitting device transmits the control information and the data packet.

Abstract: A method and device are disclosed from the perspective of a first remote User Equipment (UE). In one embodiment, the method includes the first remote UE establishing a first Sidelink (SL) Data Radio Bearer (DRB) for transmission to a second remote UE via a relay UE, wherein the first SL DRB is identified by a Radio Bearer (RB) Identity (ID). The method further includes the first remote UE ciphering a sidelink packet to be sent to the second remote UE on the first SL DRB based on at least the RB ID.

Abstract: A method and apparatus are disclosed from the perspective of a first User Equipment (UE) in RRC_CONNECTED to request sidelink resources. In one embodiment, the method transmits a first RRC (Radio Resource Control) message to a network node, wherein a presence of a sidelink QoS (Quality of Service) information list in the first RRC message is optional.

Abstract: A method and apparatus are disclosed from the perspective of a communication device. In one embodiment, the method includes the device being configured with a plurality of resource pools by a base station for a cell. The method further includes the device receiving a grant from the base station, wherein the grant indicates a resource associated with a resource pool of the plurality of resource pools through a resource pool index in the grant. The method also includes the device using the resource to perform a transmission on a device-to-device interface.

Abstract: A method and apparatus are disclosed from the perspective of a network node. In one embodiment, the method includes the network node configuring a UE (User Equipment) with a first DRB (Data Radio Bearer), wherein the first DRB is configured with a presence of SDAP (Service Data Adaptation Control) header and the network node is not allowed to reconfigure the first DRB with an absence of SDAP header before the first DRB is released. The method further includes the network node configuring the UE to serve a first QoS (Quality of Service) flow and a second QoS flow by the first DRB. The method also includes re-configuring the UE to serve the first QoS flow by a second DRB, which was originally served by the first DRB, if the second QoS flow is released or removed from the first DRB, wherein the second DRB is configured with an absence of SDAP header.

Abstract: A method and apparatus are disclosed from the perspective of a first UE (User Equipment) in RRC_CONNECTED to detect configuration failure. In one embodiment, the method includes the first UE transmitting a first PC5 RRC (Radio Resource Control) message to a second UE, wherein the first PC5 RRC message includes an AS (Access Stratum)-layer configuration for a unicast link established with the second UE. The method also includes the first UE transmitting a fourth RRC message to a network node if a configuration failure of the AS-layer configuration is detected, wherein the fourth RRC message indicates the configuration failure occurs.